Fire-resistant glass fiber knit fabric

ABSTRACT

Disclosed is a fire resistant knit fabric skeleton having a plurality of knit loops formed of corespun glass fibers, with every other course in the knit further containing a bare glass fiber, such that alternating courses of the knit fabric are either entirely corespun glass fiber or a combination of corespun glass fiber and bare glass fiber. The fabrics a unique mix of favorable properties such as excellent fire resistance and strength, improved coating adhesion, a lower basis weight, and high cross machine direction extensibility.

FIELD OF THE INVENTION

The invention herein pertains to fabrics in general and more particularly pertains to a fire-resistant knit fabric made of glass fibers.

DESCRIPTION OF THE PRIOR ART AND OBJECTIVES OF THE INVENTION

Fire resistant fabrics find use in a wide variety of applications, such as protective clothing, upholstery, clothing, and household furnishings (drapes, carpet, bedding). Generally speaking, fire resistant (or fire retardant) fabrics are made from inherently non-flammable fibers or by treating an otherwise flammable material to render it fire retardant or fire resistant. In addition, the fire-resistant fabric may be made as a finished fabric, or as a so-called “skeleton” fabric that may then be laminated, coated or otherwise treated before being used for its intended application. The fabrics and skeletons may be of knit, woven or nonwoven construction.

U.S. Patent Application Publication No. 2016/0183694 teaches a fire resistant double knit fabric having a first side containing a fire retardant yarn, a second side containing a charring yarn, and a middle layer, disposed between the first and second layers, comprising a middle yarn. The fire retardant yarns and charring yarns may be wrapped around a structural filament, such as glass fiber. The structural filament may be present in the fabric in amounts of 15 to about 45%. The charring yarns are modacrylic, cellulose, wool of combinations thereof. The fire retardant yarn may be an inherently fire retardant fiber or fibers treated with a fire retardant. The middle yarn can be a fire retardant yarn or a charring yarn, or combinations thereof.

U.S. Patent Application Publication No. 2007/0004302 teaches a flame resistant matelasse fabric, which is a type of three-layer, double knit fabric. The top layer of the fabric is formed of standard, non-flame retardant fibers such as cotton, nylon, wool, acrylic, etc. while the middle and bottom layers are formed from fire resistant yarns. More specifically, the fibers used to make the middle and bottom layers include at least oxygen depleting fibers (i.e., polymers and copolymers made from halogenated monomers) and non-flame resistant fibers mentioned above for the top layer. The middle and bottom layers may also contain inherently fire resistant fibers such as melamine fibers, aramid fibers, polybenzimidazole fibers, partially oxidized polyacrylate fibers, polyimides, etc.

U.S. Pat. No. 4,690,859 teaches a breathable fire barrier fabric comprising a glass fiber fabric coated with an encapsulating coating to minimize or eliminate fiber-to-fiber self-abrasion. The encapsulating coating comprises a binder, fillers, fire retardant, additives, foaming agents and optionally includes pigments and/or plasticizers. The encapsulating coating adheres to the glass fiber fabric even when subjected to heat and flames. The glass fiber fabric may be a woven fabric, a nonwoven fabric or a knit fabric. The coated fiber glass fabric has a porosity less than about 300 ft³/min./ft² at 0.5 inch water pressure, and preferably less than about 250 ft³/min./ft².

U.S. Pat. No. 5,540,980 teaches a fine textured fire resistant flame barrier fabric used for mattress and pillow ticking, bedspreads, mattress covers, draperies and other furnishing and clothing applications. The fabric is formed from a corespun yarn having a high temperature resistant continuous filament fiberglass core (20-40 wt. %) and low temperature resistant staple fiber sheath (60-80 wt. %) surrounding the core. The staple fibers forming the sheath may be natural or synthetic and include cotton, wool, polyester, etc. and the sheath may include chemical treatments to enhance the formation of a char (as opposed to ash) when exposed to heat/flames. The corespun yarns may be woven or knitted in a single end or non-plied manner.

U.S. Pat. No. 4,987,026 teaches a flame retardant coated fabric article having a single layer of fabric comprised of glass fibers and natural or synthetic fibers and covered on one side by a thermoplastic polyvinyl halide composition. The glass fibers are said to provide strength to the article so that the article does not tear apart when subjected to flames under tension and the thermoplastic coating is capable of forming a char to enhance the effectiveness of the article as a flame barrier. The fabric contains about 10-90 wt. % of glass fibers and 90-10 wt. % of natural or synthetic fibers, other than glass and has a basis weight of 1.5 to 5.5 ounces per sq. yard. The fabrics are said to be superior to prior art fire resistant fabrics made entirely of glass fibers in that they do not require specially formulated adhesives to adhere to the glass fibers, they have better drape and hand, and have better stretch/extensibility than all glass fiber fabrics. The glass fibers are preferably woven in both directions but may also be spun into yarn and made into a knit construction. In such knit constructions, the glass fibers may be used in one direction and the non-glass fibers used in the other direction, but it is preferred that both the glass and non-glass fibers are in each direction. This can be accomplished by alternating glass and non-glass fibers in the weave or knit, or more preferably by incorporating the glass and non-glass fibers into a spun yarn with the glass fibers forming the core of the yarn and the non-glass fibers forming a sheath around the core. Preferably, the glass fiber core comprises 30-50 wt. % of the resulting yarn with the sheath comprising the remaining 50-70 wt. % of the yarn.

Despite the breadth of materials in the prior art, there remains a need for a fire resistant fabric having low basis weight, good fire resistant properties and good stretch/extensibility for specialized upholstery applications.

Accordingly, it is an objective of the present invention to provide a fire-resistant glass fiber knit fabric which will provide better fire resistance with a lower basis weight.

It is another objective of the present invention to provide a fire-resistant glass fiber knit fabric which will maintain good stretch/extensibility qualities.

It is still another objective of the present invention to provide a fire-resistant glass fiber knit fabric formed from knitted together bare glass fibers and corespun glass fibers.

It is yet a further objective of the present invention to provide a fire-resistant glass fiber knit fabric in which the knitted glass fiber fabric alternates between all corespun glass fibers and a combination of corespun glass fibers and bare glass fibers.

It is still yet a further objective of the present invention to provide a fire-resistant glass fiber knit fabric having a unique mix of favorable properties such as excellent fire resistance and strength, improved coating adhesion, a lower basis weight, and high cross machine direction extensibility.

Various other objectives and advantages of the present invention will become apparent to those skilled in the art as a more detailed description is set forth below.

SUMMARY OF THE INVENTION

In a preferred embodiment, the fire resistant fabric of the invention has bare glass fibers and corespun glass fibers knitted together to form a glass fiber fabric, characterized in that the courses in the knit fabric alternate between all corespun glass fibers and a combination of corespun glass fibers and bare glass fibers. The fabrics of the instant invention provide excellent fire resistant with lower basis weight and still maintain good stretch/extensibility in the cross machine direction (i.e., the weft direction). In a particularly preferred embodiment, the fabric is defined by the stitch a lock stitch knit fabric.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an enlarged plan view of the front side or face of the fire resistant fabric according to a preferred embodiment of the invention; and

FIG. 2 is a plan view of the back side of the fabric of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT AND OPERATION OF THE INVENTION

The preferred fabric of the invention is a circular knit fabric containing bare glass fibers and corespun glass fibers. The bare glass fibers are fibers having a glass filament and no sheath or coating. The corespun glass fibers are fibers having a glass filament as a core and a sheath of non-glass fiber. Such corespun fibers are well known and discussed above in the aforementioned Publication Nos. 2016/0183694 and 2007/0004302, and U.S. Pat. Nos. 4,690,859, 5,540,980, and 4,987,026. The disclosures of these references are incorporated herein in their respective entireties.

The fabric preferably has a basis weight of between about 5 ounces per square yard and about 6 ounces per square yard, and is most preferably about 5.5 ounces per square yard. The corespun glass fibers comprise between 60 wt. % and 80 wt. % of the fabric, more preferably between 68 and 78 wt. %, and most preferably between 72 and 75 wt. %. The bare glass fibers may be from 20 wt. % to 40 wt. % of the fabric, more preferably between 22 and 32 wt. % and most preferably between 25 and 27 wt. %. The fabric skeleton described herein may be further processed by methods known in the art for particular applications, such as coating the skeleton with halogenated polymers or other fire resistant compositions, laminating the skeleton to foams or textiles, etc. In particular, the fabric skeleton of the invention has improved coating adhesion as compared to fabrics made of all corespun glass fibers or alternating course of corespun fibers and bare glass fibers.

The fabric of the invention may be made by any known knitting process that will produce the desired pattern. In making the fabric, every other feed includes a bare glass fiber and a corespun glass fiber and alternates with feeds that contain only corespun glass fiber. Thus, for example, feeds 1, 3 and 5 can include bare glass and corespun glass fibers whereas feeds 2, 4 and 6 can contain only corespun glass fiber. Stated another way, in making the fabrics of the invention all feeds include corespun glass yarns, whilst every other feed also includes a bare glass fiber.

The fabrics disclosed herein meet the requirements of the ASTM D6413 Vertical Flame Test. By selecting appropriate components, laminated structures made using the fabrics of the invention are capable of meeting FTPC Part 8 of IMO Res. A.652(16): Test for Upholstered Furniture. The fabrics disclosed herein have an extensibility (measured in the cross machine direction) of at least 100% under a static load of 10 pounds (4.54 kg) and preferably at least 125% under such load. This extensibility makes the fabrics particularly well-suited for use in upholstery and other applications requiring a high degree of drape or conformity.

With reference to FIGS. 1 and 2, a preferred embodiment of the fire resistant fabric of the invention is illustrated therein. The fabric 10 comprises a plurality of loops characteristic of a knit fabric. The fabric illustrated in FIGS. 1 and 2 is a weft knit fabric known as a lockstitch (due to its formation being defined by a lockstitch pattern), which is a more robust knit as compared to, for example, a jersey knit, and is thus the preferred construction of the fabric of the invention. Other knit patterns, however, may also be used. As seen the Figures, the fabric 10 comprises corespun glass fibers 14 wherein every other course or feed includes a bare glass fiber 12.

The illustrations and examples provided herein are for explanatory purposes and are not intended to limit the scope of the appended claims. 

We claim:
 1. A knit fabric comprising successive courses of corespun glass fibers, wherein every other course of said fabric comprises a bare glass fiber in combination with said corespun glass fiber.
 2. The fabric of claim 1, wherein the fabric comprises a circular knit fabric.
 3. The fabric of claim 1, wherein the fabric comprises a lockstitch fabric.
 4. The fabric of claim 1, wherein the fabric has a basis weight of about 5 to about 7 ounces per square yard.
 5. The fabric of claim 1, wherein the fabric has a basis weight of about 5.5 ounces per square yard.
 6. The fabric of claim 1, wherein the fabric comprises a lockstitch fabric and has a basis weight of about 5.5 ounces per square yard.
 7. The fabric of claim 1, said fabric consisting entirely of corespun glass fibers and bare glass fibers.
 8. The fabric of claim 1, wherein the corespun glass fibers comprise about 60 to about 80% by weight of the fabric.
 9. The fabric of claim 1, wherein the corespun glass fibers comprise about 68 to about 78% by weight of the fabric.
 10. The fabric of claim 1, wherein the corespun glass fibers comprise about 72 to about 75% by weight of the fabric.
 11. The fabric of claim 1, wherein the bare glass fibers comprise about 20 to about 40% by weight of the fabric.
 12. The fabric of claim 1, wherein the bare glass fibers comprise about 22 to about 32% by weight of the fabric.
 13. The fabric of claim 1, wherein the bare glass fibers comprise about 25 to about 28% by weight of the fabric.
 14. The fabric of claim 1, wherein the fabric comprises a lockstitch fabric having a basis weight of about 5.5 ounces per square yard and wherein the corespun glass fibers comprise about 68 to about 78% by weight of the fabric.
 15. The fabric of claim 1, further comprising a coating on at least one side of the fabric.
 16. The fabric of claim 1, further comprising a halogenated polymer coating on one side of the fabric.
 17. The fabric of claim 1, further comprising foam laminated to at least one side of the fabric.
 18. The fabric of claim 1, further comprising a textile laminated to at least one side of the knit fabric. 